Express your answer as a mixed number simplified to lowest terms. $17\dfrac{6}{7}-8\dfrac{7}{8} = {?}$
Answer: Find a common denominator for the fractions: $= {17\dfrac{48}{56}}-{8\dfrac{49}{56}}$ Convert ${17\dfrac{48}{56}}$ to ${16 + \dfrac{56}{56} + \dfrac{48}{56}}$ So the problem becomes: ${16\dfrac{104}{56}}-{8\dfrac{49}{56}}$ Separate the whole numbers from the fractional parts: $= {16} + {\dfrac{104}{56}} - {8} - {\dfrac{49}{56}}$ Bring the whole numbers together and the fractions together: $= {16} - {8} + {\dfrac{104}{56}} - {\dfrac{49}{56}}$ Subtract the whole numbers: $=8 + {\dfrac{104}{56}} - {\dfrac{49}{56}}$ Subtract the fractions: $= 8+\dfrac{55}{56}$ Combine the whole and fractional parts into a mixed number: $= 8\dfrac{55}{56}$